Air cleaning apparatus

ABSTRACT

Air cleaning apparatus including a wall over which a film of water is passed into a sump having a water level spaced below the bottom of the wall. The spray laden air passes under or through openings in this wall into a washer for removing particulate material. A screw conveyor scrapes the top of the wall to remove deposits. In one embodiment the air is withdrawn from an opening at a level above the washer and passes downwardly through the washing zone.

Unite States Patent [1 1 Arnold et a1.

[ Mar. 26, 1974 AIR CLEANING APPARATUS Inventors: Orlan M. Arnold, Norwalk; Carlo A.

Vancini, Stamford, both of Conn.

Peabody Engineering Corporation, New York, NY.

Filed: May 25, 1972 Appl. No.: 256,963

Assignee:

U.S. Cl 55/223, 55/227, 55/239, 55/241, 55/248, 55/257, 98/115 SB,

261/112, 261/118, 26l/DIG. 44, 26l/DIG. 54 Int. Cl BOld 47/02, BOld 47/10 Field of Search 55/220, 221, 226, 228, 55/239, 244, 248, 250, 252, 257, 258, 259, 223, 240; 261/116, 117, DIG. 44, DIG. 54, 112, 118, 18, 30; 118/326, 422, 634, DIG. 4, DIG. 7; 210/530; 61/18, 30; 56/400.01; 98/115 SB References Cited UNITED STATES PATENTS 11/1949 Liebel 118/422 X 10/1950 Loney 98/115 SB 2,899,183 8/1959 Umbricht 55/257 X 2,906,511 9/1959 Umbricht et a1. 55/257 X 2,989,836 6/1961 Schafi'er 56/4000! 650,569 5/1900 Shaw 222/405 2,539,340 l/1951 White 222/405 3,426,729 2/1969 Hawkins 1 18/326 X FOREIGN PATENTS OR APPLICATIONS 7,935 3/1905 Great Britain 118/422 Primary Examiner-Dennis E. Talbert, .lr.

Assistant ExaminerNeil F. Greenblum Attorney, Agent, or FirmN. L. Leek; Robert H. Bachman 5 7] ABSTRACT 13 Claims, 7 Drawing Figures PAIENIEU mas m4 skrsaseo PAIENIEMR26 m4 3.798.880

SHEET 2 [IF 5 llllllll AIR CLEANING APPARATUS This invention relates to air cleaning apparatus for use in cleaning air within an enclosure, such as a room, or for cleaning air containing spray particles.

An object is to provide novel and improved means for efficiently removing and cleaning air which may be laden with droplets of a spray or with other particulate material.

Another object is to improve the quality of air in an enclosure and also to reduce or eliminate contamination of the outside atmosphere into which the air is discharged.

A more specific object is to provide an apparatus for use in connection with a paint spray or the like, which is adapted to remove the contaminations from the air efficiently before discharging air into the surrounding atmosphere.

Various other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

In accordance with the present invention a wall toward which the air is advanced is covered by a water film which flows downwardly along the surface of the wall to form a flood sheet. The wall may be inclined to the vertical to facilitate the washing of the wall by the downward flow of water if desired. This water is collected in a sump below the bottom of the wall under which the air flows into a washing zone wherein contaminants are removed. After washing, the air passes through a drying zone to remove the wash liquid and is then discharged into the atmosphere or recirculated.

The nature of the invention will be better understood from the following description, taken in connection with the accompanying drawings in which certain specific embodiments have been disclosed for purposes of illustration.

In the drawings:

FIG. 1 is a vertical longitudinal section through air washing and drying apparatus embodying the invention;

FIG. 2 is a partial section taken on the line 22 of FIG. 1 showing the details of the device for cleaning the top portion of the flood sheet;

FIG. 3 is a longitudinal section, similar to FIG. 1, illustrating a further embodiment of the invention;

FIG. 4 is a partial transverse section taken on the line 4-4 of FIG. 3 illustrating a further form of cleaning element for removing deposits from the top portion of the flood sheet;

FIG. 5 is a longitudinal section, similar to FIG. 3, and illustrating a still further embodiment of the invention;

FIG. 6 is a top plan view of an apparatus adapted to be disposed as a unit in an enclosure for air cleaning purposes; and

FIG. 7 is a vertical section taken on the line 77 of FIG. 6.

Referring to the drawings more in detail, the invention is shown in FIGS. 1 and 2 as embodied in an enclosure 10, which may constitute a room of any size containing dust or spray laden air which is to be cleaned. The enclosure 10 has side walls 11 between which an air cleaning unit including a flood sheet 12 is disposed in a position such that the air from the enclosure is withdrawn over the flood sheet and into a cleaning unit in a manner to be described. The unit may, for example, be disposed near the end of the enclosure or at one side thereof so that the flood sheet l2 forms in effect one of the walls of the enclosure. A layer or film of water or other solvent is continuously passed over the flood sheet for entrapping and removing particulate material from the air which contacts the flood sheet and for removing any deposits of such material therefrom.

The top of the flood sheet forms a weir 15 over which wash liquid flows from a channel 16. The rear wall 17 of the channel 16 may contact the ceiling, not shown, of the enclosure 10 to prevent the passage of air between the ceiling and the unit. The sides of the flood sheet 12 may likewise form an air seal with the side walls 11 of the enclosure so that all of the air is caused to pass through the cleaning unit. Water or other solvent is supplied to channel 16 by suitable means such as pipe 19, and flows over the weir 15 and downwardly over the surface of the flood sheet 12 into a reservoir 20.

The reservoir 20 is disposed on the floor 21 of the enclosure 10 and carries a liquid layer 22 from which the bottom of the flood sheet 12 is spaced to provide a passage 23 for air flow out of the enclosure 10. The flood sheet 12 is shown as inclined to the vertical by a small amount so as to cause the water film to flow along its surface in its path from the weir 15 to the reservoir 20. It may however extend vertically if desired.

In order to remove accumulated deposits of material from the top of the flood sheet 12, a screw type scraper 25 is disposed along the top edge 15 and is formed with helical vanes which scrape along the top surface as the screw is rotated. This scraper is journalled in bearing blocks 26 at each end and is rotated by a motor 27 through a gear box 28. The bearing blocks 26 are pivotally supported on rear wall 17 and are adjustable by threaded rods 29 which are supported by brackets 30 and are provided with cranks 31 at their upper ends. These threaded rods permit the screw 25 to be adjusted relative to the top edge 15.

The screw 25 may be rotated continuously for cleaning the top edge of the wall or may be elevated out of the path of the liquid when not in use.

A housing 35 enclosing a washing and drying zone is disposed rearwardly of the flood sheet 12 above the reservoir 20. The drying zone is formed by a pair of baffle plates 36 which extend across the housing 35 in spaced relationship and are formed with openings 37 communicating with drying units 38 which are adapted to remove entrained liquid droplets by impingement and by inertia as the air flows therethrough in a curved path as shown more in detail in copending US. Pat. application Ser. No. 155,916, filed June 23, l97l (P-l70). While this specific type of drying unit is shown for purposes of illustration, it is obvious that other standard types of dryer units may be used in the present combination.

The washed and dried air is discharged by a blower 40 which serves to induce the flow of air from the enclosure 10 and through the washing and drying zones.

The washing zone includes a washing unit disposed above an opening 46 in a cover 47 for the reservoir 20. A curved deflector plate 48 extends across the housing 35 with its lower end 49 spaced above the level of the liquid layer in the reservoir 20 so that the air from the washing unit 45 passes downwardly under the lower edge 49 of the deflector plate 48 and then upwardly into the drying zone. Due to this reversal in direction the heavier droplets in the air stream are caught in the liquid layer in the reservoir and are removed from the air stream.

An inner concentric post 50 is carried by a water pipe 51 which extends through the deflector plate 48 and is provided at its lower end with a spray head 52 to direct a spray of water across the annular passage 53 between the wall of the unit 45 and the inner post 50. In order to improve the washing operation a constricting ring 54 may be disposed in the unit 45 at or above the level of the water spray from the spray head 52.

Air washing apparatus of this type is shown more in detail in the copending application above mentioned. However, other standard types of gas washing units may be used in the present combination if desired. If the flood sheet is sufficiently wide laterally a plurality of such washing units may be disposed along the wall to communicate with a succession of openings in the cover 47 and the washed air from the entire group may be passed into the drying zone above described. The flood sheet 12 may be supported by the cover 47 and by the housing 35. The reservoir 20 extends beyond the flood sheet to form a sump adapted to receive the liquid which flows downwardly over the flood sheet.

In operation the spray or dust laden air in the enclosure is withdrawn continuously from the enclosure and is passed under the flood sheet into the washing zone wherein the contaminants are removed by the kinetic energy of the spray liquid from the spray head 52. Larger particles are removed into the liquid in the sump by inertia as the air stream reverses in direction under the flood sheet 12. Any particles which impinge on the water film on the flood sheet are also discharged into the liquid in the reservoir 20.

After washing the air is reversed in direction to flow downwardly by the deflector plate 48 and is again reversed as it flows under the lower edge 49 of the deflector 48 and upwardly into the drying zone. Thus, additional droplets are removed by inertia and the remaining Thus material is removed in the drying zone by the baffle plates 36. The clean air may be discharged into the atmosphere or may be recycled as desired.

In the embodiment of FIG. 3 the enclosure 55 is similar to that of FIG. 1 except that the flood sheet is composed of two parts 560 and 56b which are relatively offset and separated by a discharge opening 57 through which the contaminated air passes into the washing zone. The upper portion 56a forms a weir 58 over which water from a channel formed by bottom wall 59 and back wall 60 flows to wash the forward surface of the flood sheet. Wash water may be supplied to this channel by an inlet pipe 19a.

For cleaning the upper portion of the weir 58 a saw toothblade 61 is mounted for longitudinal movement on a bar 62, as by pins and slots 63 and may be reciprocated by any suitable means such as a link 64. The bar 63 is mounted for vertical adjustment on blocks 66 which are carried on threaded vertical rods 67 having adjusting handles 68. The arrangement is such that the blade can be raised or lowered or oscillated to scrape the upper portion of the weir as desired and may be elevated out of the path of the liquid when not in use.

The lower edge of the flood sheet 56b forms a water seal with the wash liquid 70 in a reservoir 71. The reservoir 71 extends beyond the flood sheet 56b and carries a cover 72 having an opening 73 registering with the bottom discharge portion of a cylindrical wash unit 74. The unit 74 has its inlet adjacent the discharge opening 57 and such air is directed into the inlet opening 75 of the unit 74 by deflector plate 76.

The unit 74 carries an axial spray nozzle 77 mounted on a spray pipe 78. This nozzle ejects a radial spray of wash water through which the gases pass. A ring member 79 may be disposed in the unit 74 to constrict the gas passage in the zone of the spray and produce a venturi-like effect.

The washed gases which are discharged from the unit flow along the air space above the liquid 70 in the reservoir 71 and upward into a drying chamber 80 having a drying element 81 adapted to remove liquid droplets from the air which is then discharged by a blower 82.

The drying unit may be of any standard type and is shown for illustration as comprising a series of curved deflector blades over which the air passes with a sufficient change in direction to remove the liquid droplets by inertia. Such a unit is shown more in detail in copending U.S. Pat. application Ser. No. 187,760, filed Oct. 8, 1971 (P-l76).

The operation of this form of spray booth is similar to that above described except that the air flows dowpwardly from the opening in the flood sheet and deposits large droplets directly into the liquid 70 in the reservoir 71 while the remaining droplets are removed by the drying unit 81. It is to be understood that the screw type scraper of FIG. 2 may be substituted for the scraper blade of FIG. 4 or vice versa as desired in any particular installation.

In the embodiment of FIG. 5 the flood sheet is arranged to discharge air both from a central opening and through a reservoir below the lower edge of the sheet. Separate washing units are provided for the two discharge zones, with both units discharging into a common drying zone.

In this figure the flood sheet is composed of upper and lower parts a and 90b having a discharge passage 91 therebetween.

The upper portion 90a is formed with a weir 92 over which liquid from a channel 93 flows as in the previous figures. The weir is provided with a screw scraper 25a which is similar to that of FIG. 1. The lower portion 90b is formed with a similar weir 94 over which liquid from a channel 95 flows in a sheet and into the reservoir 20a. Wash water may be supplied to the channels 93 and 95 by inlet pipes 19b. The two portions 90a and 90b are substantially in line so that liquid which flows downwardly over the surface of the upper portion 90a is collected in the lower channel 95 and flows down over the surface of the lower portion 90b into the reservoir 20a. The lower weir may have a cleaning device such as the scraper blade of FIG. 4 or the screw scraper of FIG. 2 if found necessary. This will depend upon the nature of the material being treated.

The reservoir 20a extends beyond the flood sheet 90b and has a cover on which is mounted a washing unit 101 similar to the unit 45 of FIG. 1. This unit has a side discharge opening 102 at its upper end and is provided with a spray head 103.

A second washing unit is mounted above the unit 101. Air discharged from the passage 91 between the upper part 900 and lower part 90b of the flood sheet is passed into the lower end of this unit 110 by deflector plates 111. The unit 110 is provided with a side discharge opening 112 at its upper end.

Washed air which is discharged from the discharge openings 102 and 112 is passed downwardly by deflector plate 114 and after passing under the lower edge 115 of this plate passes into the drying zone 116 having a drying unit 117 similar to that above described in connection with FIG. 3 or of other standard type in which the entrained droplets are removed. The dried air is then discharged by a blower 118.

The operation of this form is similar to that above described except that the air stream is split into two parts which are separately washed. The washing units in FIG. 5 are shown as of the updraft type. It is to be understood, however, that these units can be of any standard type and may be used in various combinations. For example the upper unit may be of the down draft type so that the discharge openings are both in the intermediate zone.

The spray heads in the two washers may be carried by the same water pipe 119 which extends along both units or they may be individiually supplied as desired.

FIGS. 6 and 7 illustrate an air cleaning unit which is generally similar to that of FIG. 3, but is adapted to be used in an intermediate position in an enclosure such as a room as distinguished from being used in a position such that the flood sheet forms one of the walls of the enclosure. In the embodiment of FIGS. 6 and 7, the unit includes four flood sheets 120 which are disposed around the periphery of the unit to form in effect an enclosure for the unit. The enclosure is shown as rectangular in form but may obviously be of any desired shape. For example, three flood sheets may be disposed in triangular relationship or a cylindrical flood sheet may be used. In any event, the flood sheets 120 are shown as inclined inwardly for the flow of water downwardly along the surface thereof, and the wash water is shown as supplied from a pipe 121 which extends along the upper portion of the respective flood sheets and is provided with suitable openings for discharging a spray of water onto the upper surface of the same. Obviously, however, the wash water may be supplied by weirs as shown in FIG. 3, if desired.

Flood sheets 120 are supported on the cover 72a of a reservoir 71a and form a water seal with the liquid therein. The reservoir 71a extends beyond the various flood sheets to form sumps into which the wash water drains, as in FIG. 3. A plurality of washing units 740 are shown as extending along the flood sheets 120 and supported by the cover 72a of the reservoir. These units 74a may be similar to the units 74 above described. Air to be cleaned is supplied through ports 122 in the flood sheets 120 and through ducts 123 to the tops of the respective washing units 74a for washing as it passes downwardly through said units into the space above the liquid in the reservoir 71a.

The washed air passes upwardly from the reservoir through a housing 124 into a drying and discharge zone, not shown, which may be similar to that described in connection with FIG. 3.

The operation of this embodiment is generally simila to that of FIG. 3 above described except that air to be cleaned is received through ports 122 around the entire periphery of the unit and after passing through the respective washing units 740 is concentrated radially into the single housing 124 and passed to suitable drying units of the type above described and is discharged into the enclosure for reuse or discharged to the atmosphere, as described.

The air cleaning apparatus above described may be used for cleaning the air in a room or for cleaning the air from a booth such as a spray booth, wherein the air is subjected to a concentrated spray such as a paint spray. The contaminants may thus be removed before the air is discharged to the atmosphere or before the air is recirculated.

We claim:

1. Air cleaning apparatus comprising a flood sheet disposed in the path of the air to be cleaned, means passing wash liquid over the surface of said flood sheet for cleaning the surface and forming a first wash zone for said air, wherein the upper part of said flood sheet forms a weir over which said liquid flows, scraper means connected to said weir and operatively constructed and arranged for removing deposits from said weir, air washing units disposed beyond said flood sheet forming a second wash zone, means passing said air from said first wash zone through said air washing units in said second wash zone, a drying zone, means passing the air from said second wash zone through said drying zone for the removal of entrained particles and droplets and means discharging the washed and dried air from said drying zone.

2. Apparatus as set forth in claim 1 including a receiver for said wash liquid extending below said flood sheet and said second wash zone and said drying zone and means discharging wash liquid and entrained particles from each of said zones into said receiver.

3. Apparatus as set forth in claim 1 in which said scraper means includes a shaft having helical vanes and means to rotate said shaft to cause said vanes to scrape the top of said weir.

4. Apparatus as set forth in claim 3 including means to adjust the position of said shaft relative to said weir.

5. Apparatus as set forth in claim 1 in which said scraper means includes a blade having a saw tooth lower edge and means for reciprocating said blade laterally and for adjusting the vertical position thereof.

6. Apparatus as set forth in claim 1 in which an air passage is provided above said liquid in said receiver and below the lower end of said flood sheet and air from said passage is passed into said second washing zone.

7. Apparatus as set forth in claim 1 in which said flood sheet comprises upper and lower portions separated by an air passage, and including means passing air from said passage through said second washing zone.

8. Apparatus as set forth in claim 7 in which the two portions of said flood sheet are substantially in the same plane.

9. Apparatus as set forth in claim 8 in which a weir is provided at the top of each of said portions for causing a wash liquid to flow downwardly over the surface of the respective portions.

10. Apparatus as set forth in claim 7 in which the upper and lower portions of said flood sheet are relatively offset to provide an air passage therebetween.

11. Apparatus as set forth in claim 7 in which said lower portion is spaced above the liquid in said receiver to form a second air passage, and air washing means is disposed in said second wash zone to receive air from each of said passages for washing.

12. Apparatus as set forth in claim 11 in which flood sheet forms an enclosure and said second wash washed air from said second wash zone is passed zone and said drying zone are disposed within said enthrough a common drying zone. closure.

13. Apparatus as set forth in claim 1 in which said 

1. Air cleaning apparatus comprising a flood sheet disposed in the path of the air to be cleaned, means passing wash liquid over the surface of said flood sheet for cleaning the surface and forming a first wash zone for said air, wherein the upper part of said flood sheet forms a weir over which said liquid flows, scraper means connected to said weir and operatively constructed and arranged for removing deposits from said weir, air washing units disposed beyond said flood sheet forming a second wash zone, means passing said air from said first wash zone through said air washing units in said second wash zone, a drying zone, means passing the air from said second wash zone through said drying zone for the removal of entrained particles and droplets and means discharging the washed and dried air from said drying zone.
 2. Apparatus as set forth in claim 1 including a receiver for said wash liquid extending below said flood sheet and said second wash Zone and said drying zone and means discharging wash liquid and entrained particles from each of said zones into said receiver.
 3. Apparatus as set forth in claim 1 in which said scraper means includes a shaft having helical vanes and means to rotate said shaft to cause said vanes to scrape the top of said weir.
 4. Apparatus as set forth in claim 3 including means to adjust the position of said shaft relative to said weir.
 5. Apparatus as set forth in claim 1 in which said scraper means includes a blade having a saw tooth lower edge and means for reciprocating said blade laterally and for adjusting the vertical position thereof.
 6. Apparatus as set forth in claim 1 in which an air passage is provided above said liquid in said receiver and below the lower end of said flood sheet and air from said passage is passed into said second washing zone.
 7. Apparatus as set forth in claim 1 in which said flood sheet comprises upper and lower portions separated by an air passage, and including means passing air from said passage through said second washing zone.
 8. Apparatus as set forth in claim 7 in which the two portions of said flood sheet are substantially in the same plane.
 9. Apparatus as set forth in claim 8 in which a weir is provided at the top of each of said portions for causing a wash liquid to flow downwardly over the surface of the respective portions.
 10. Apparatus as set forth in claim 7 in which the upper and lower portions of said flood sheet are relatively offset to provide an air passage therebetween.
 11. Apparatus as set forth in claim 7 in which said lower portion is spaced above the liquid in said receiver to form a second air passage, and air washing means is disposed in said second wash zone to receive air from each of said passages for washing.
 12. Apparatus as set forth in claim 11 in which washed air from said second wash zone is passed through a common drying zone.
 13. Apparatus as set forth in claim 1 in which said flood sheet forms an enclosure and said second wash zone and said drying zone are disposed within said enclosure. 